The mechanism by which growth conditions, notably the carbon source, regulate intracellular concentrations of cyclic AMP in Escherichia coli will be studied. A more extensive knowledge of just how much metabolism of a compound is needed to produce significant changes will be performed using mutants with a variety of metabolic lesions, including those affecting the phosphotransferase system. In vitro assays of adenylate cyclase using concentrated cell extracts will be used to determine if any of a large number of metabolic intermediates have any regulatory effect on the activity of this enzyme. Regulatory effects of the E. coli cyclic AMP binding protein on adenylate cyclase activity will be examined. Attempts will be made to isolate cyclic AMP phosphodiesterase mutants to determine what role this enzyme plays in regulation.